Secondary Productivity-2 Dr. Jason Turner MARE 444

Ichthyoplankton Planktonic fish Mainly eggs and larval fish (fry) Seasonal, locally important in planktonic food webs Prey and predators

Fish Embryonic Development Oviparous release eggs into water column Ovoviviparous eggs kept inside mother, embryos obtain nourishment from egg yolk Viviparous embryos obtain nourishment directly from mother

Ichthyoplankton Most bony fishes (Osteichthyes, teleosts) are oviparous Eggs are either released into the water column, attached to the bottom, sometimes guarded by adult fish

Fish eggs Some fish release eggs into the water column Planktonic eggs are typically 1-2 mm in diameter Oil droplets may be present for flotation 25,000 to 100 million eggs released per female Fewer larger versus many smaller

Fish eggs High nutrient content Dietary component Important to life histories

Fish fry Rate of embryo development is dependent on species and temperature (few days to weeks) Temperature effects faster development smaller adults lower fecundity

Fry survival Early life mortality 99.999% in cod Size matters (temperature?) chase down prey escape from predators Critical phase – endogenous → exogenous when yolk is used up - there better be food around r-selection

Patchiness Individuals are not distributed uniformly or even randomly makes research difficult (non-parametric statistics) Lots versus none

Why does patchiness occur? Circulation patterns Frontal boundaries Food distributions Migratory movements Nutrient content

Factors Limiting Ocean Nutrients 1. Nutrient content not constant 2. Production reduced at depth 3. Organisms reduce water volume 4. Nutrients absorbed by other autotrophs

Eddy Haulani West Longitude

Langmuir Circulation Constant wind sets up small-scale vortices Upwelling and downwelling can occur (upper few meters only) Concentrates organic particles at surface Parallel lines of foam/debris/rift

Other Examples of Patchiness Reproduction Feeding Schooling